Hydrocarbon inhibitor for use in heat exchangers of oil refinery equipment



United States Patent 3,328,285 HYDROCARBON INHIBITOR FOR USE IN HEAT EXCHANGERS OF OIL REFINERY EQUIPMENT Richard L. Godar, St. Louis, Mo., assignor to Petrolite Corporation, Wilmington, Del., a corporation of Delaware No Drawing. Continuation of application Ser. No. 50,558, Aug. 19, 1960. This a plication Jan. 6, 1965, Ser. No. 423,853

5 Claims. (Cl. 208-48) This application is a continuation-in-part of application Ser. No. 33,903, now abandoned, having a common assignee and now abandoned, and this application is a continuation of application Ser. No. 50,558, filed on Aug. 19, 1960, now abandoned.

This invention relates to a method of chemically treating hydrocarbon liquids which contact surfaces under high temperature conditions in order to inhibit, prevent and/ or reduce the deposition of substances thereon. More specifically, this invention relates to the chemical treatment of the metal surfaces in contact with petroleum hydrocarbon liquids under conditions of high temperatures whereby said liquids tend to form deposits on such metal surfaces. This invention also relates to compositions employed in these processes.

In the processing of hydrocarbon liquids, particularly petroleum hydrocarbon liquids, elevated temperatures are often used in many necessary and important operations. To handle liquids at elevated temperatures, heat exchangers and the like devices are often employed to control the heat transfer rate from one operational step to another. When hydrocarbon liquids contact hot metal surfaces, there is sometimes a tendency for the liquid to decompose or undergo a chemical reaction that manifests itself in the form of deposits. These deposits may be either coke-like or they may be in the form of tenacious, soft sticky sludges which adhere to hot surfaces. Adherence of deposits, rather than deposit-formation itself is the essence of the problem, in contrast to fuel storage where residue in the oil itself creates the problem.

The problem is well recognized in the artNote Petroleum Products Handbook, Guthrie (McGraw-Hill, 1960), pages l13, US. Patent 2,908,824, and elsewhere.

These deposits tend to materially decrease the heat transfer capacities of the metal surfaces and hence increase operating expenses. These deposits also require additional effort and time to remove and to restore the equipment to its original operating efiiciency.

Petroleum refinery operations often encounter the above described conditions in many stages in the refining process. These deposits form on heat transfer surfaces at temperatures as low as about 200225 F. and may be evidenced at temperatures as extreme as 800 F.

It is practically impossible to prevent these deposits by coating the metal surfaces with a protective permanent coating due to the possible loss of heat transfer. In addition, the large volume of liquid that contacts such equipment increases the problem of treating metal surfaces in petroleum processing to prevent high temperature deposits.

It would be advantageous if a chemical agent could be added in an extremely small amount to a hydrocarbon liquid which tends to form high temperature deposits whereby such deposits would be prevented. It would also be desirable if such a chemical would not only prevent such deposits but would also remove them without necessitating the stoppage of a given operation. It therefore becomes an object of the present invention to prevent the formation of high temperature deposits on metal surfaces by chemical means.

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Another object is to furnish a chemical which when added to a hydrocarbon liquid will prevent the depositforming tendencies of said liquid when it contacts metal surfaces at elevated temperatures.

A further object is to provide a chemical treatment which will prevent the formation of high temperature deposits by petroleum hydrocarbon liquids in contact with heat transfer equipment.

Yet another object is to furnish a chemical treatment capable of being combined with a thermally unstable, deposit-forming liquid whereby said liquid will not form deposits upon metal surfaces at elevated temperatures.

Still another object is to provide a chemical treatment which will remove high temperature deposits from metal surfaces of petroleum refining equipment without the necessity of stopping the operations of such equipment. Other objects will appear hereinafter.

In accomplishing these objects in accordance with the invention it has been found that new and improved results in preventing, inhibiting and/or reducing the formation of deposits from petroleum hydrocarbon liquids during the processing thereof at elevated temperatures, particularly at temperatures within the range of about ZOO-225 F. to 800 F., are obtained by adding to, preferably by dissolving or dispersing in the hydrocarbon liquid, a partial ester of a polyol and a carboxylic acid, said partial ester being soluble and/ or dispersible in the hydrocarbon liquid, wherein at least one but not all of the hydroxy group of the polyol are esterified with a carboxylic acid. Although the partial ester can be employed alone, its activity is enhanced by one or more of the following oil soluble or dispersible auxiliary agents:

(1) An oxyalkylated phenol.

(2) A copolymer of (a) an acrylic type ester and (b) vinyl pyrrolidone (sometimes referred to herein as copolymer) (3) A metal deactivator.

The anti-fouling agent employed in this invention is a partial ester of a polyol and a carboxylic acid. Although partial esters formed from monocarboxylic acids are preferred, partial esters of polyols and polycarboxylic acids, particularly dicarboxylic acids, can be employed provided they are soluble or dispersible in hydrocarbon, for example a partial ester polymer of a diol and a dicarboxylic wherein B is the acid moiety (an alkylene, arylene, cycloalkylene, etc. radical) and G is the polyol moiety (an alkylene, oxyalkylene, polyoxyalkylene, etc. radical). Another example of a suitable partial ester of a dicarboxylic acid and a diol is i t? HOGOCBCOGOH Examples of polycarboxylic acids include the alkylene polycarboxylic acids, the arylene polycarboxylic acids, the aralkylene polycarboxylic acids, etc. Specific examples of dicarboxylic acids include where B is alkylene, arylene, etc., for example, succinic, alkenyl succinic, glutarlc, adipic, pimelic, suberic, azelaic, sebacic, dimeric etc. acids. Examples of aromatic dicarboxylic acids include phthalic, isophthalic, terephthalic acid, biphenyl dicarboxylic acid, etc.

Examples of polyols include diols, triols, tetrols, pentols, hexols, etc. for example glycols, glycerol, polymerized glycerols, trimethylol ethane, sorbitol, mannitol, mannide, mannitan, sorbide, sorbitan, pentaerythritol, etc.

Examples of glycols include the alkylene glycols, HO- alkylene-OH, for example where the alkylene group has 2-20 or more carbons but preferably 2-8 carbons, with an optimum of 2-4 carbons and polyoxyalkylene glycols, for example of the formula, HO(all ylene-O),,H where the alkylene group is, for example, ethylene, propylene, butylene, mixtures or blocks thereof, etc. and n is 1-100, for example 1-20, but preferably 1-10. Non-limiting examples include ethylene glycol, propylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, tripropylene glycol, pentaethylene glycol, pentamethylene glycol, decamethylene glycol, hexadecamethylene glycol, heptadecaethylene glycol, the Pluronics of Wyandotte Chemical Company, etc.

A class of partial esters utilizable in this invention include esters of hexitans and hexides obtained by dehydrating sorbitol, and. certain polyoxyalkylenes, such as the polyoxyethylene and derivatives thereof. These compounds are known as Spans and Tweens, which are manufactured by the Atlas Powder Company. According to the manufacturers literature, these esters are prepared by first dehydrating sorbitol to produce a mixture of hexitans and hexides having the following formula:

and condensed furan ring This mixture of hexitans and hexides is then esterified by reacting it with one or more moles of a fatty acid to form the Spans. The Tweens are similar thereto except that the unesterified hydroxy groups in the hexitans and hexides have polyoxyethylene chains added thereto. Non-limiting examples of the esters contemplated herein are sorbitol anhydride monolaurate, sorbitol, anhydride monomyristate, sorbitol anhydride monopalmitate, sorbitol anhydride monostearate, sorbitol anhydride monooleate, sorbitol anhydride monolinoleate, and polyoxyethylene derivatives of the foregoing monoesters. Further data on the monoesters utilizable herein are attainable in a brochure entitled Atlas Surface Active Agents, published in 1948 by the Atlas Powder Company. Reference should be made thereto, and it is considered to be a part of this specification.

I advantageously employ a compound of the formula where R is an alkylene radical derived from an alkylene oxide, for example ethylene oxide, propylene oxide, butylene oxide, etc., and Where R is the group derived from the carboxylic acid, for example, an aliphatic group, a cycloaliphatic group, an aryl group, substituted groups thereof, etc., but preferably an alkyl group having sufficient carbons therein to make the product oil soluble or dispersible for example 6-20 or more carbons with an optimum of 10-20 carbons. In the preferred embodiment the polyol should have at least one unesterified hydroxyl group, for example in the case of glycerol, one or two of the hydroxyl groups thereon are esterified by the carboxylic acid. These compounds, having at least one unesterified hydroxyl group, will be referred to herein as partial esters and can be expressed generally as 0 (HO)X' G (O(HJ' RI)Y where R is the radical derived from the carboxylic acid and G is the radical derived from the polyol and x and y are each at least 1 and the sum of x+y equals the number of hydroxyl groups originally present in the polyol.

Although the partial esters alone prevent fouling, their efiiciency is often enhanced by the presence of other auxiliary chemical components.

One of these auxiliary chemical components is an oxyalkylated phenol, preferably an oxyalkylated hydrocarbon-substituted phenol, such as an alkyl phenol, for example those of the formula Rllm where R is an alkoxy radical or hydrocarbon group, such as an aryl radical, an aliphatic radical, preferably alkyl,

for example containing 1-30 or more carbon atoms, such as 4-20 carbons, but preferably 8-18 carbons, A is an alkylene radical derived from an alkylene oxide such as ethylene, propylene, butylene, etc. oxides added singly, mixed, blocked, etc., x represents the number of moles of alkylene oxide for example 1 to or more, such as 1-20, but preferably 1-10 and m represents the number of substituted groups, for example 1-2.

An example of an oil-soluble or dispersible polyalkylene ether of an alkyl phenol is prepared by alkylating phenol with an olefin containing at least 6, and preferably 9 to 18, carbon atoms under conditions adapted to furnish an alkyl phenol reaction product having an average of 1 to 2 alkyl groups per phenol molecule. The olefins employed for the alkylation of phenol may be straight-chain olefins, such as those produced in the Fischer-Tropsch synthesis; branched-chain olefins, such as those formed in the polymerization of propylene and butylene; or mixtures of branchedand straight-chain olefins which are recovered from a heavy cracked naphtha by selective adsorption with silica gel. Alcohols or alkyl chlorides with carbon chains of suitable length may be also employed as the alkylating agents. Preferably, mixture of C to C branched-chain olefins produced by polymerizing propylene are thus employed. The resulting alkyl phenol product which may contain from 15 to 20% by weight of dialkyl phenols, is condensed with ethylene oxide, propylene oxide, butylene oxide, individually or in combination, or a corresponding glycol. Ethylene oxide is usually preferred. Particularly suitable alkyl phenyl polyoxyalkylene ethers are alkyl phenyl polyoxyethylene ethers containing an average of 10-20 alkyl carbon atoms and l to 10 oxyethylene groups.

Another auxiliary chemical component is the copolymer derived from an acrylic ester of the formula:

and N- vinyl-2-pyrrolidone, for example a copolymer containing the following units:

having a molecular weight for example of at least 50,000, for example 50,000500,000, or higher, but preferably 100,000-400,000 with an optimum of 300,000-400,000 of which vinyl pyrrolidone comprises at least 1% by weight of the copolymer, for example 1-30%, but preferably 3-15 with an optimum of 5-10%; where Y is hydrogen, a lower alkyl group such as methyl, ethyl, etc., Z is an hydrocarbon group having, for example, 1-30 carbon atoms, but preferably 8 to 18 carbon atoms. These polymers are preferably acrylic or methacrylic polymers, or polymers derived from both in conjunction with vinyl pyrrolidone. The Z group on the polymer, which can be the same throughout or mixed, can be octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, octadecyl, etc. Lower alkyl groups can also be employed such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, etc., but they preferably are employed as copolymers of the higher Z groups, for example a copolymer of dodecyl methacrylate and methyl acrylate, etc. The acrylic ester units may be derived from one or more acrylic type monomers and may be fully acrylic or fully methacrylic or both acrylic and methacrylic. The polymer may be random, block, graft, etc.

Also, Z may also be an alkylated aromatic group such as butyl phenyl, amyl phenyl, etc., or a cycloaliphatic group such as cyclohexyl. Thus, non-limiting specific examples of suitable monomeric esters are: methyl acrylate, ethyl acrylate, propyl methacrylate, amyl acrylate, lauryl acrylate, cetyl acrylate, octadecyl acrylate, amyl methacrylate, lauryl methacrylate, cetyl methacrylate, octadecyl methacrylate, amylphenyl methacrylate, cyclohexyl methacrylate, etc., including the analogous acylate or methacylate esters. Copolymers of the above and other acrylic esters may be used, for example, a copolymer of methyl or ethyl acrylate and dodecyl methacrylate in conjunction with vinyl pyrrolidone. However, it should be understood that this description does not preclude the presence of small amounts of unesterified groups being present in the polymer, i.e. approximately 5% or less of where Z=H.

It should be understood, of course, that when the above compounds are polymerized, the polymerization should not be carried to such an extent as to form polymers which are insoluble or non-dispersible in the petroleum hydrocarbon used. The polymerization may be carried out by methods known to the art, such as by heating mildly in the presence of a small amount of benzoyl peroxide, but the method of polymerization is not part of this invention. For examples of acrylic-vinyl pyrrolidone copolymers, see French Patent 1,163,033.

Another auxiliary chemical component is a metal deactivator for example those conventionally employed in deactivating copper, iron and other metals from hydrocarbon systems. Typical examples are those described in U.S. Patent 2,282,513. Of course, one skilled in the art is aware that many other metal deactivators are known and can be employed herein.

The compounds employed as metal deactivators are preferably of the type of Schilfs bases and may be represented by the formulae wherein A and B each represents an organic radical and preferably a hydrocarbon radical. In Formula 2 A and B each preferably represents an aromatic ring or an unsaturated heterocyclic ring in which the hydroxyl radical is attached directly to a ring carbon atom ortho to the -CH=N group. R represents an aliphatic radical having the two N atoms attached directly to different carbon atoms of the same open chain.

Typical examples of aldehydes and olyamines employed in preparing these Schitf bases include the following.

Aldehydes:

Benzaldehyde Z-methylbenzaldehyde S-methylbenzaldehyde 4-methylbenzaldehyde 2-methoxybenzaldehyde 4-methoxybenzaldehyde u-Naphthaldehyde fl-Naphthaldehyde 4-phenylbenzaldehyde Propionaldehyde n-Butyraldehyde Heptaldehyde Aldol 2-hydroxybenzaldehyde 2-hydroxy-6-methylbenzaldehyde 2-hydroxy-3-methoxybenzaldehyde 2,4-dihydroxybenzaldehyde 2,6-dihydroxybenzaldehyde 2-hydroxynaphthaldehyde-1 1-hydroxynaphthaldehyde-2 Anthrol-2-aldehyde-1 2-hydroxyfluorene-aldehyde-1 4-hydroxydiphenyl-aldehyde-3 3-hydroxyphenanthrene-aldehyde-4 1,3-dihydroxy-2,4-dialdehyde-benzene 2-hydroxy-5-chlorobenzaldehyde 2-hydr.oxy-3,S-dibromobenzaldehyde 2-hyrlroxy-3-nitrobenzaldehyde 2-hydroxy-3-cyanobenzaldehyde 2-hydroxy-3-carboxybenzaldehyde 4-hydroxypyridine-aldehyde-3 4-hydroxyquinoline-aldehyde-3 7 -hydroxyquinoline-aldehyde-8 Polyamines Ethylenediamine 1,2-propylenediamine 1,3-propylenediamine 1 6-hexamethylenediamine 1,10-decamethylenediamine Diethylenetriamine Triethylenetetramine Pentaerythrityltetramine 1,2-diaminocyclohexane Di-(B-aminoethyl) ether Di-(B-aminoethyl) sulfide The partial ester comprises at least 5% of the antifouling composition such as 5 to 100%, for example 10 to preferably 15 to 60% with an optimum of 30 to 40%.

Where other auxiliary chemical components are employed in conjunction with the partial ester, they are employed in the following percentages of the total composition.

Oxylated phenol-0 to for example 10 to 80%, preferably 30 to 70%, with an optimum of 40 to 60%.

The copolymer-0 to 35%, for example 1 to 25%, preferably 5 to 15% with an optimum of 8 to 12%.

Metal deactivators0 to 10%, for example .0001 to 8%, preferably 0.1 to 5 with an optimum of 0.5 to 2%.

Thus, the partial ester may be eifectively employed alone or in conjunction with the oxyalkylated phenol, and/ or the copolymer and/ or the metal deactivator. However, it should be noted that the optimum amounts of each will vary with the fuel, the conditions employed, the temperatures, etc.

The conditions encountered in refinery operations are simulated by exposing petroleum products taken from various refineries to high temperature heat exchange tubes in the absence of and in the presence of the antifouling compositions of this invention.

A CFR fuel coker Model OIFC is employed to simulate these conditions. It is described in CRC Manual No. 3, March 1957, published by the Coordinating Fuel and Equipment Research Committee of the Coordinating Research Council, Inc. The standard procedure is employed except that the equipment is modified so as to bypass the filter section.

The conditions of the test are stated in the following OP=oxya1kylated phenol, specifically nonyl phenol, 10 moles EtO).

Ar=copolymerspecifically a copolymer of stearyl methacrylate and vinyl pyrrolidone (7.5%), average molec- (oxyethylated ditable. The amount of fouling occurring is measured by ular weight 350,000. weighing the preheater (or heat exchanger) tube before OP =oxyethylated didodecyl phenol. and after the test to determine the amount of deposits MD=metaldeact1vator specifically, formed on the preheater tube.

Another method of measuring fouling is simply to observe its appearance, and this is normally also done. One generally finds tube appearances to correspond with the amount of fouling measured by gravimetric means, for example, a tube showing 2.0 mg. deposit will look considerably cleaner than one showing 4.0 mg. deposit. It should be noted that the gravimetric results described in Table I were generally corroborated by an inspection of the tube CH in each case. H H C=NCH CH N=C The symbols in the table have the following meanmg. 2 l

DGL=diethylene glycol monolaurate, specifically Ho OH H HOCHzCHz 0 011201312 0 C(CH2)10CH;

Test Test Test Test Rate Additives Employed P. .m. of MI. Ex. Time, Temp., Pressure, Flow. Ratio of @otal Foul ing Mln. F. p.s.1. lbs/hr. 1 2 3 Additives Additives Material 011m. 1 Naphtha Charge 450 150 3 None 3 9 40 450 150 3 DGL 100 0'5 40 450 150 3 DGL Ar 3:1 37 40 450 150 3 DGL Ar 3:1 73 40 450 150 3 OP 2'0 120 450 150 3 None 14 120 450 150 3 DGL 111 450 3 01 75 120 450 150 3 01? DGL 3:4 38 120 450 150 3 OP DGL Ar 4.5:3:1 71 120 450 150 3 OP Ar 22:1 55 120 450 150 3 OP DGL Ar 22:31 77 120 450 150 3 OP DGL Ar 7.5:3:1 72 9' 120 450 150 3 OP DGL Ar 45:3:1 71 120 450 150 3 Ar 34 1 1 Oil No. 2 Naphtha Charge 230 450 150 3 None 9 6 230 450 150 3 OP DGL Ar 4.5 3:1 71 4' 230 I 450 150 3 OP DGL Ar 4.5 3:1 35 '2 230 450 150 3 01 DGL Ar 4.5 3:1 1

Oil N o. 3 Naphtha Charge 120 450 150 3 None 6 g 120 450 150 3 OP DGL Ar 45:3:1 43 3' 120 450 150 3 OP DGL Ar 4.5:3:1 24 120 450 150 3 OP DGL Ar 45:3:1 12 4' 120 450 150 3 OP DGL Ar 45:3:1 7 120 450 150 3 OP DGL Ar 45:3:1 2 1 Oil No. 4 Naphtha Charge 230 450 150 3 None 3 7 2s 230 450 150 3 OP DGL Ar 4.5:3:1 12 27 Oil No. 5 Naphtha Charge 120 450 150 3 None 9 9 120 450 150 3 OP DGL Ar 4.53 1 95 4'1 120 450 150 3 OP DGL Ar 45:3 1 24 71 Oil No. 6 Straight Run Gasoline 230 450 150 3 None 3 7 g; 230 450 150 3 OP DGL Ar 45:3:1 43 13 93 4571354263217 41936 6 9 03848 37 4569 t 3 2 eaaaoaalaaata 2 .1 aLLao 7 3 1 6 5 2 1 0 n-m 211111111 1 mw oa M S RW 85 5 5 5 n n n n e an a 11.1. anm nn 3 a no a n n anm am wT P A s u and. 11.11111 1 1 11 1 A n vnu 5 555 55555555 o 5 no 5 .m 5 .Mu m A. 4 41 4Z4 A4 4-4 4 4 a 41 4A A a 4i 1 M r Tar-l rrrrrrrr rrrr r r tr r r r rr m A w. AAA AAAAAAAA w. AAAA A A m. AA A m. A m. A a AA 0 r. r r a a M m m m h h h h m C C C C C C C e a a a a a a m 2 m L m. LLL LLLLLLLL m LLLL L L m LL L m L m L m LL 8 h h .W m G w. GGG GGGGGGGG m. GGGG G G W GG .G G .G w GG v o D N DDD DDDDDDDD N DDDD D D N DD D N D N D N DD M 7. aw m u m B M M 0 0 m m N N N N 1 n "H u oo\)8\/6\l 1 l 1 l O m 0 n m 0 e mun t w m m m m m m e m m 0P PPPoPPPPPPPP mPPPPEPEPE oPPoP 0P mP oPPP No N000N00000000 N0000 0 0 NO0N0 N0 N0 N000 m s 33 3333333333333 33333 3 3 33333 33 33 3333 -1 RW tlfiw Fb 1 T I 00 0000000000000 00000 0 0 00000 00 00 0000 m MM HHUUUUHHUUUHH UUHHU U H UUHUU UN UH UHHU as Twp. P I 00 0000000000000 00000 0 0 00000 00 00 0000 o.. fififififififififififififi M%%%% fi fififififi M 4 fif mmF TED T 00 00000 0 0 00000 00 00 0000 66 HHMHE m H mmmmm mm MM HMMH fir 1 Contains 0.9% MD, based on weight of total additive composition.

The above tests are typical of the screening tests emthe oxyalkylated phenol, and (3) the copolymer, typical weight percentage compositions are as follows.

ployed in evaluating anti-fouling additives. These are run on both aluminum and steel heat exchange tubes. After being screened in this manner, the anti-fouling additives are employed in petroleum refinery operations with results that corroborate those obtained above. By means of the above tests, the most effective additive or mixture of additives is selected for the particular hydrocarbon under consideration and the additive is then employed in the specific operation.

As determined from the above tests in conjunction with 70 refinery operations, the most universally successful additive is a mixture of the partial ester in conjunction with the oxytalkylated phenol, and the acrylic polymer. In certain instances the metal deactivating agent is also helpful.

Where the additive includes (1) the partral ester, (2)

B. Cyclic type: [RCOLZKCHZCEDQ 1 1] I YZ fumn, pyran or condensed [nran ring 5 Ex. n z x Commercial RC Name Where the metal deactivator is employed, it is .001 to 8%, preferably 0.1 to 5%, with an optimum of 0.5 to 2%, 1 3 2 Tween based on the above mixture. 1 3 2 Tween 18 1 3 2 Tween 81. The following table illustrates the use of the preferred g g 10 gween s5. 1 10 ween 65. mlxed anti-fouhng agents. 1 3 1O Tween 2-. 1 3 10 Tween 80. 23"". 1 3 0 Span 20. 24..." 1 3 0 Span 40. 25- 1 3 0 Span 60.

TABLE II Ratio of Additive DGLzOPzAr Ex. Type 011 Heat Exchanger F. Inlet Fl Inlet Time in Throughput,

System Temp. Temp. Operation bbli/day Components Ppm.

Ratio 1 Naphtha (Charge to Re- Carbon Steel 220 460 324i :1 11 120 days 1,100

ormer 2 d0 ----J" 250 500 314.521 9.5 90 days 11,000

The above tests, in terms of pressure build-up due to TABLE IV. OXYALKYLATED PHENOLS the formation of deposits and the inspection of the d1s- (0A) 0H mantled equipment, are superior to the same oil employing no additive and to the oil containing the commercial additive formerly employed in the operation. 35

In addition to the examples presented above, the following compounds are satisfactorily employed as antifoulants. Rm

TABLE III.-PARTIAL ESTE RS 40 A. Linear type Ex. R In AO n Ex. Polyol Acid Mole Ratio POlYOI/Afiid 1 o 3 150 20 Ethylene glycol Dodecanoic 1:1 1 Diethylene glycol Napl1themc(M.W. 1:1 1 Eto 220-230). 2 o 30 Propylene glycol 1:1 2 Eto 15 Dipropylene glycol 1:1 1 Eto 25 3 2 PrO 10 1 1 2 BuO 5 2 1 2 Pro 15 1 1 {Pro 5 1.2 EtO 3 Lflllllc 121 1 o 10 Trimethylnonanoic 1:1 Pr 0 3 nounonmrom Hexanoic 1:1 1 7 P t l r'tol Laurie 1 3 Eto 15 en aer 1 i 1 a sorbiw1$ 0181c: 1:2 ydr g t d ardm l mo Mannitol Palmltic 1:3

TABLE V.VINYL'PYRROLIDONE-ACRYLIC ESTER-TYPE RESINS Vinyl Ex. Monomer 1 Monomer 2 Monomer 3 Pyrrolidone, M01 Ratio Weight Percent by 1:223

Wgt.

1 Tridecyl methaerylate. Octadeeyl methacrylate 7 5 2 Dodeeyl mothacrylata 10 3 do 15 4 Octadecyl methacrylate 5 5 Tridecyl mcthacrylate 20 Octodecyl mcthacrylate" 10 7 ii i Dodccyl methacrylete. 5 8 Cetyi mcthacrylote Oetadecyl methacry 5 The anti-fouling additive can be employed in refining crude petroleum as well as in the treatment of any component thereof which are exposed to high temperatures including the light distillates, for example light naphthas, intermediate naphthas, heavy naphthas, etc.; middle distillates, for example kerosene, gas oil, etc.; distillate lube oil stocks, for example, white oil, saturating oil, light lube oil, medium lube oil, heavy lube oil, and the like.

In addition, the additive can be employed with other hydrocarbons such as xylene, benzene, purified hydrocarbon compounds, etc. In addition, they can be employed under certain conditions with non-hydrocarbons, such as alcohols, phenols, etc. For example, they can be employed in a toluene extraction tower and stripper which process comprises mixing phenol and toluene in an extraction whereby phenol extracts impurities from toluene and the rafiinate is subsequently removed. Thereafter the mixture is sent to a stripper Where the toluene is removed from the phenol by distillation. The remaining phenol is recycled to the extractor for further use. The system is operated over .a wide temperature range for example 230-425" F. Deposits in the phenol circuit cause the loss of excessive amounts of phenol. It can be used in heat transfer uni-ts used in a furfurol extraction process processing for example, intermediate distillates, paraffin distillates, decanted oil, vacuum cylinder stock, deasphalted cylinder stock, etc.

The amount of anti-fouling agent required in this in vention is subject to wide variation but in general very effective results have been obtained by adding relatively minute amounts of the anti-fouling agent to the hydrocarbon liquid being processed, for example, amounts may be as low as 0.5 p.p.m. in hydrocarbon liquid, for example 1 to 500 p.p.m. or higher, for example 1000 or more p.p.m., preferably 5 to 30 p.p.m., with an optimum of -20 p.p.m. In general, the upper limit is determined by the economics of the process but other factors should be taken into consideration such as whether large amounts will have any adverse effects on present or subsequent operations. Because of the many different types of operations where hydrocarbons are heated to elevated temperatures under conditions where deposits are formed, it is difficult to give specific ranges which will be effective in all operations. The amount of agent which inhibits the formation of deposits is referred to herein as an antifouling amount. The above figures relate to p.p.m. in terms of active anti-fouling chemical not including the solvent employed.

Inasmuch as the anti-fouling agent is employed in such small amounts and it is preferable to feed them continuously or semi-continuously by means of a proportioning pump or other suitable device to the particular hydrocarbon liquid being processed or to add them in a similar manner to the apparatus in which the hydrocarbon liquid is being processed, it is desirable to incorporate the agent or a mixture of agents into a suitable solvent which will be compatible with the liquid which is to be processed. The solvent which is used to dissolve the active ingredient is also subject to some variation depending upon the solubility characteristics of the particular compound employed. In some cases, even though the active mixture is insoluble in a particular solvent, it will dissolve in a combination of solvents.

In the practice of the invention it is very desirable to start the treatment with the chemicals employed for the purpose of the invention at a higher dosage, say 20 to 50 p.p.m. or more of a composition and then gradually reduce the dosage to the point where fouling of the apparatus is just eliminated.

The invention is especially valuable where sour napthas are being processed or where the oil being processed is a mixture containing some sour naphthas.

Examples of specific types of apparatus to which the chemical compositions of the invention can be added during petroleum processing are fractionating towers, stripping columns, debutanizers, depropanizers, deethanizers,

heat exchangers, reboilers, hot product lines and other metal equipment (usually ferrous metal) which is brought into contact with the organic liquids being processed at relatively high temperatures. The invention makes it possible to extend the useful life of crude oil fractionating towers and other types of petroleum refinery equipment. It also makes it possible to provide cleaner inside surfaces resulting in better fractionation, better heat exchange in coolers, far less severe plugging and less time required for cleaning and maintenance.

Having thus described my invention what I claim as new and desire to obtain by Letters Patent is:

1. A process for inhibiting in oil refining apparatus during petroleum refining operations the formation of adherent coke-like deposits and adherent tenacious soft, sticky sludges on, and the adhesion of said deposits and said sludges to, the hot metal heat transfer surfaces of a heat exchanger in said oil refining apparatus by a hydrocarbon liquid passing through said heat exchanger at a temperature in excess of about 225 F. and having the tendency to undergo a chemical reaction at a temperature in the range of about 225 F. to 800 B, said chemical reaction manifesting itself in the form of adherent cokelike deposits and adherent soft, sticky sludges, such as are usually formed during passage of said hydrocarbon liquid through said heat exchanger in said oil refining apparatus and in contact with the hot metal surfaces of said heat exchanger in said oil refining apparatus at a temperature in the range of about 225 F. to 800 F. comprising (1) incorporating in said hydrocarbon liquid prior to contact with said hot metal surfaces of said heat exchanger in said oil refining apparatus an anti-fouling amount of a partial ester selected from the group consisting of (HO)r-G(OC-R) where G is the hydrocarbon-containing moiety of a HOCH and then esterifying said mixture by reacting it with at least one mole of a fatty acid selected from the group consisting of lauric acid, stearic acid, palmitic acid and oleic acid, and

I (4) partial esters formed by first dehydrating sorbitol to produce a mixture of hexitans and hexides having the formula C CH-CHzOH then esterifying said mixture by reacting it with at least one mole of a fatty acid selected from the group consisting of lauric acid, stearic acid, palmitic acid and oleic acid, and then adding polyoxyethylene chains to the nonesterified hydroxy groups in said hexitans and hexides, and

(2) heating said hydrocarbon liquid having incorporated therein said partial ester in an antifouling amount to a temperature in the range of about 225 F. to about 800 F. by contact with said hot metal surfaces of said heat exchanger in said oilrefining apparatus.

2. A process for inhibiting in oil refining apparatus during petroleum refining operations the formation of adherent coke-like deposits and adherent tenacious soft, sticky sludges on, and the adhesion of said deposits and said sludges to, the hot metal heat transfer surfaces of a heat exchanger by a hydrocarbon liquid passing through said heat exchanger at a temperature in excess of about 225 F. and having the tendency to undergo a chemical reaction at a temperature in the range of about 225 F. to about 800 F., said chemical reaction manifesting itself in the form of adherent coke-like deposits and adherent soft, sticky sludges, such as are usually formed during passage of said hydrocarbon liquid through said heat exchanger and in contact with the hot metal surfaces of said heat exchanger in said oil refining apparatus at a temperature in the range of about 225 F. to about 800 F. comprising (1) incorporating in said hydrocarbon liquid prior to contact with said hot metal surfaces of said heat exchanger in said oil refining apparatus an antifouling amount of a composition comprising (A) a partial ester selected from the group consisting of Where G is the hydrocarbon-containing moiety of a polyol,

x is an integer of at least 1,

y is an integer of at least 1, the sum of x and y being equal to the number of hydroxyl groups originally present in the polyol, and

R is a hydrocarbon radical having 6-20 carbon atoms selected from the group consisting of an aryl radical and an aliphatic radical (2) a partial ester of a polyol and a polycarboxylic acid,

16 (3) partial esters formed by first dehydrating sorbitolto produce a mixture of hexitans and hexides having the formula and then esterifying said mixture by reacting it with at least one mole of a fatty acid selected from the group consisting of lauric acid, stearic acid, palmitic acid and oleic acid, and

(4) partial esters formed by first dehydrating sorbitol to produce a mixture of hexitans and hexides having the formula 0 Cfiz CHCHzOH H0(')Bi CH-OH CfiOH HOCHCHOH (EH2 CH-CH-CHz (IJH OH then esterifying said mixture by reacting it with at least one mole of a fatty acid selected from the group consisting of lauric acid, stearic acid, palmitic acid and oleic acid, and then adding polyoxyethylene chains to the nonesterified hydroxy groups in said hexitans and hexides, and

(B) a member selected from the group consisting (1) an oxyalkylated hydrocarbon-substituted phenol having the formula where A is an alkylene radical having 2-4 can bon atoms,

m is an integer of 1-2,

x is an integer of 1-20, and

R" is a hydrocarbon-containing radical having 1-30 carbon atoms selected from the group consisting of an alkoxy radical, an aryl radical and an aliphatic hydrocarbon radical,

17 (2) a copolymer containing the units b -CH2--(IJH /N (3H1 (3:0 CH2CH2 and having a molecular Weight of 50,000- 500,000, unit (b) being at least 130'% by weight of the copolymer, Y being selected from the group consisting of hydrogen and a lower alkyl group and Z being a hydrocarbon radical having l-30 carbon atoms, and (3) a Schifi base 'alkylene polyamine-aldehyde reaction product, and (2) heating said hydrocarbon liquid having incorporated therein said composition in an antifouling amount to a temperature in the range of about 225 F. to about 800 F. by contact with said hot metal surfaces of said heat exchanger in said oil refining apparatus. 3. The process of claim 1 wherein the partial ester is of the formula H (O-alkylena) n O -R where n=1-'10 and R is an alkyl radical having 6-20 carbon atoms.

4. The process of claim 2 wherein the partial ester has the formula H[O (CHzCH2) 11120 -R where n is an integer 2-4, and R is an alkyl radical having 6-20 carbon atoms. 5. The process of claim 2 wherein the partial ester is 18 and the oxyalkylated hydrocarbon-substituted phenol is (no y a the copolymer is a copolymer wherein Y is CH and Z is stearyl in unit (a) and the Schiff base polyamine-aldehyde reaction product is References Cited UNITED STATES PATENTS 2,282,513 5/1942 Downing et a1. 4473 2,284,267 5/ 1942 Downing et al. 44-73 2,548,347 4/1951 Caron et al. 44-66 2,866,729 12/1958 Zimpel 25251.5

FOREIGN PATENTS 822,620 10/1959 Great Britain.

OTHER REFERENCES DELBERT E. GANTZ, Primary Examiner.

PAUL M. COUGHLAN, A. RIMENS,

Assistant Examiners. 

1. A PROCESS FOR INHIBITING IN OIL REFINING APPARATUS DURING PETROLEUM REFINING OPERATIONS THE FORMATION OF ADHERENT COKE-LIKE DEPOSITS AND ADHERENT TENACIOUS SOFT, STICKY SLUDGES ON, THE ADHESION OF SAID DEPOSITS AND SAID SLUDGES TO, THE HOT METAL HEAT TRANSFER SURFACES OF A HEAT EXCHANGER IN SAID OIL REFINING APPARATUS BY A HYDROCARBON LIQUID PASSING THROUGH SAID HEAT EXCHANGER AT A TEMPERATURE IN EXCESS OF ABOUT 225*F. AND HAVING THE TENDENCY TO UNDERGO A CHEMICAL REACTION AT A TEMPERATURE IN THE RANGE OF ABOUT 225*F. TO 800*F., SAID CHEMICAL REACTION MANIFESTING ITSELF IN THE FORM OF ADHERENT COKELIKE DEPOSITS AND ADHERENT SOFT, STICKY SLUDGES, SUCH AS ARE USUALLY FORMED DURING PASSAGE OF SAID HYDROCARBON LIQUID THROUGH SAID HEAT EXCHANGER IN SAID OIL REFINING APPARATUS AND IN CONTACT WITH THE HOT METAL SURFACES OF SAID HEAT EXCHANGER IN SAID OIL REFINING APPARATUS AT A TEMPERATURE IN THE RANGE OF ABOUT 225*F. TO 800*F. COMPRISING (1) INCORPORATING IN SAID HYDROCARBON LIQUID PRIOR TO CONTACT WITH SAID HOT METAL SURFACES OF SAID HEAT EXCHANGER IN SAID OIL REFINING APPARATUS AN ANTI-FOULING AMOUNT OF A PARTIAL ESTER SELECTED FROM THE GROUP CONSISTING OF 